The program consists of four major areas: 1) Structural and functional studies of connective tissue, serum and membrane proteins including cartilage constituents and fibronectin. 2) Humoral immunity including the structure, function, biosynthesis and genetic control of immunoglobulins and factors involved in the regulation of antibody synthesis. In parallel and complementing this, there is an active program devoted to the structure of certain complement components and their interaction with cellular receptors. Clinically, these studies converge on patients with immune complex diseases and patients with lymphoproliferative or plasma cell disorders. 3) Cellular mechanisms in diseases. In particular there is a multidisciplinary collaborative effort to define subsets of monocytes, to study the role of surface enzymes in normal and disordered monocyte function, and to correlate the structure and function of various subsets of lymphocytes. These studies focus on the amyloid diseases and various lymphoid neoplasms. 4) Genetics, development and membrane structure. The main focus of this work is to evaluate the role of genetic factors in resistance to leukemia and to study various surface components of lymphoid cells coded by the major histocompatibility locus that behave as differentiation markers and may play a role in lymphocyte function and cell-cell interaction.